I highly doubt we will get any announcement of Marsden or Famke. Since all films are canon they are still dead for now, I think they will show up but that would be giving away plot twists saying they are back. Unless they start with an Alt timline their return will be a result of the films conclusion. They wont want to give that away. But hey ya never know with these films...

Now that people are excited I suspect the FC crew will be announced next. Followed by a few new actors not introduced in the series yet.